The present invention is particularly useful in packaging frangible dosage forms which are easily damaged during transport of the package and easily damaged by the user upon opening. The disclosures of commonly assigned U.S. Pat. Nos. 5,178,878 and 5,223,264, which are hereby incorporated by reference herein, describe one form of relatively soft tablets which are susceptible to damage. These tablets include, in addition to the active ingredients, an effervescent composition so that when the tablet is orally administered to a patient, it disintegrates. These tablets are very soft with a hardness typically below about 20 Newtons and in some cases below 10 Newtons.
Pharmaceutical dosage forms, such as pills, capsules, tablets and the like, may be packaged in blister packages, which are comprised of multi-layered sheets of material having pockets for containing the dosage forms. Conventional blister packages include packages having a foil layer through which a user of the package must push the tablet, breaking the foil. Hall et al., U.S. Pat. No. 4,158,411, discusses such a blister package. Blisters having open tops for containing pharmaceutical tablets are formed in a flexible sheet of plastic material. A paperboard layer having disc-shaped punch-outs covers the open tops of the blisters overlying each dosage form. A foil layer covers the paperboard layer, holding the punch-outs in place. To open the package, the user must collapse the blister and push the tablet through the foil, also removing the punch-outs. This push-through package would damage soft tablets and other frangible dosage forms when the user pushes the package to collapse the blister. In addition, the tablet or other dosage form is free to shift within the blister, presenting the opportunity for the dosage form to become damaged upon transport.
Another type of blister package provides perforations between separable blister units so that the user can separate an individual dosage from the package prior to opening. U.S. Pat. No. 4,398,634 to McClosky, illustrates a blister package of this type. The blister portions are defined by tear-resistant, substantially planar plastic sheets sealed to one another in seal zones. The seal zones are located around the periphery of each blister unit, forming pockets of unsealed areas which define the blisters, centrally located in the blister unit. Weakened areas in the seal zones allow the user to separate the blisters into individual units by tearing a unit away from the package. Upon separation of the unit, the user tears through the plastic layers, through the blister, to gain access to the dosage form. A slit in the corner of the unit is provided for easy tearing. During separation of a unit from the package, the plastic tends to tear through the remaining blisters in the package, destroying the package. Each weakened area meets at a central uncut area provided to reduce tearing through the remaining blisters in the package. Because the user is required to tear through a blister to gain access to the dosage form, frangible tablets in a package of this type would be destroyed by the user upon opening the package.
Another type of blister package includes individual units which, upon separation, reveal a tab for opening the blister. U.S. Pat. No. 5,046,618 to Wood discloses this type of blister package. The blister package is formed from a sheet of material having blisters formed therein and a substantially planar lidding sheet. This blister package has two rows of blisters, each blister unit separated from an adjacent unit by perforations. The rows are separated by tear strips with perforations between the tear strips and the blister units. To open the package, a user separates an individual unit from the package with a tear strip still attached to the unit. This tear strip must be removed to access the tab, which comprises an unsealed area on the corner of the blister unit. After the tear strip is removed, the user grabs the corner of the lidding sheet and peels the sheet back to reveal the dosage form. It is not disclosed that the package protects frangible dosage forms from becoming damaged.
Indicia provided on blister packages could be directed to guiding the user in opening the package so as to avoid damage to the dosage form. U.S. Pat. No. 3,503,493 to Nagy discloses indicia visible from the top side of the blister package, the side opposite the side having blisters, indicating the type of pharmaceutical contained in the package. U.S. Pat. No. 4,158,411 to Hall et al. discusses indicia for guiding the user regarding a schedule for consuming the pharmaceutical contained in the package. The indicia are reference numerals corresponding to each dosage, indicating to the user when a dose must be taken. The indicia discussed in U.S. Pat. No. 5,511,665 relates to the opening of the package but is provided as a diversion, to direct children to disarm the package so that it cannot be easily torn open.
Thus, despite the substantial time and effort expended to solve the problems associated with packages for dosage forms, further improvement in such packages would be desirable.